Polymers of 3,4-substituted pyrrole compounds and their preparation method

ABSTRACT

Polymers of a 3,4-substituted pyrrole compound substituted by an electron-attractive group having a Hammett&#39;s substituent constant (σ p ) of 0.30 to 0.80 in at least one of the 3- and 4- positions are disclosed. The polymers are stable in the air in a dope-free state and show distinct electrochromism. Some of them are soluble in an alkaline aqueous solvent. Therefore, they are useful as electrochromic elements, etc.

TECHNICAL FIELD

This invention relates to new polymers of pyrrole compounds and moreparticularly to the polymers of 3,4-substituted pyrrole compounds, theirpreparation method and the laminates of the polymer on an electrodeplate.

BACKGROUND TECHNOLOGIES

The electrochemical polymerization of 5-membered and 6-memberedheterocyclic compounds, particularly of pyrrole, is laid open in thespecification of U.S. Pat. No. 3,574,072.

That the anodic oxidative polymerization of pyrrole in the presence of aconductive salt results in forming film with the conductivity of lessthan 10² S cm⁻¹ on the anode is described in A. F. Diaz, et. al: J.C.S.Chemical Communication (J.C.S. Chem. Comm. P635 (1979)).

It is defined in this technical field that polymer film containing theanion of the conductive salt and formed on the anode is said to be dopedin the P type (oxidation state) and the state of which the anion, adopant, is taken out from the inside of the molecule is said a undopingstate (reduction state). The polymer film is known to have highconductivity in the doping state and extremely low conductivity in theundoping state, and to display the electrochromism when changing betweenthe two states.

The polymers of 3,4-substituted pyrrole, especially of3,4-asymmetrically substituted pyrrole compounds have generaldescriptions but few of them have been synthesized. No documentsdescribing particularly polymers of pyrrole compounds having an electronattractive substituent at C₃ or C₄ have not been yet known.

The aforementioned polymer film of pyrrole compounds display theelectrochromism, and have however no clear beautiful color changes. Whenletting stand alone in the air in the undoping state, the film isoxidized to change the color to black and thus does not exist stable inthe undoping state. The polymers are usually insoluble and not melting.

Therefore, industrially useful materials or electronic devices employingthe film have not been obtained yet.

INDICATION OF INVENTION

The present invention aims at offering the new polymers of3,4-substituted pyrrole compounds, which have clear color changes andexist stable in the air even in the undoping state, and theirpreparation methods.

This invention has particular purposes of offering the polymers of3,4-asymmetrically substituted pyrrole compounds and the polymerssoluble in alkaline aqueous solvents, among the above polymers.

In addition, an offer of the laminates made by laminating the film ofthe said polymer on an electrode plate and applicable as electro chromiccomponents is also one of the purposes of the invention.

This invention relates to that a pyrrole compound represented by thefollowing general formula (1) ##STR1## (where at least one of X and Y isan electron attractive substituent with 0.30-0.80 of the Hammett'ssubstituent constant (σp), and if only one of X and Y is the aboveelectron attractive substituent, the other is hydrogen, an alkylradical, a benzyl radical, or a non-substituted or substituted phenylradical, and Z is hydrogen or an lower alkyl radical) is polymerized byelectrolytic oxidation in the presence of a conductive salt, or bychemical oxidation in the presence of an oxidizing agent, resulting ingiving the polymers of 3,4-substituted pyrrole compounds, which arerepresented by the following general formula (2) ##STR2## (where X, Yand Z have the same meaning as the above and n is an integer of 2 orlarger).

In this invention, the pyrrole compound used as a material and itspolymer have, as depicted in general formulae (1) and (2), at least anelectron attractive substituent with the Hammett's substituent constant(σp) within the range of 0.3-0.80 at C₃ or C₄. The substituent includesNO₂, --SO₂ NH₂, --CF₃, --OCF₃, --SCF₃, --CN, --NCS, --CHO, --COOH, --CH₂COOH, --CONH₂, --CONHOH, --SOR, --SO₂ R, --OSO₂ R, --CF₂ CF₃, --COR,--SCOR, --OCOR, --COOR, --CONHR, --CHNOR, --CHNNHC(S)NH₂, --P(R)₂ D,(O)(OR)₂, --C(OH)(CF₃)₂, --N₂ C₆ H₅, --SO₂ C₆ H₅, --OSO₂ C₆ H₅, --COC₆H₅, --CO₂ C₆ H₅, --CHNC₆ H₅ or --P(O)(C₆ H₅)₂ (where R stands for astraight chain or branched alkyl radical having from 1 to 10 carbonatoms). Particularly preferred one includes --COOH, --COOR, --NO₂, --CN,--COR, --CONH₂ or --CONHOH (where R is a straight chain or branchedalkyl radical having from 1 to 10 carbon atoms).

These various compounds can be used singly or as a mixture, as thematerial pyrrole compound.

Of the above pyrrole compounds and their polymers, those of which onlyeither C₃ or C₄ is substituted by one of the above electron attractivegroup are said to be 3,4-asymmetrically substituted pyrrole compoundsand their polymers. In this case, the other position of C₃ or C₄ hashydrogen, a straight-chain or branched alkyl radical having from 1 to 10carbons, a benzyl radical, a phenyl radical or a phenyl radicalsubstituted by a halogen, nitro, cyano, methoxy or ethoxy radical.

Of the above polymers, those of which at least one of X and Y is an acidsubstituent such as --COOH or --CH₂ COOH (if only one of them is thestated acid substituent, the other is hydrogen, an alkyl radical havingfrom 1 to 3 carbons or a phenyl radical) are soluble in alkaline aqueoussolvents.

In addition, the polymers of the 3,4-substituted pyrrole compounds ofthis invention can form film on an electrode plate to be laminates.

BRIEF DESCRIPTION ON DRAWINGS

FIG. 1 shows the instruments used for the measurement of electrochromicproperties.

(Symbols used)

1. Main body of cell

2. VIS-UV spectroscope

3. ITO glass plate

4. Polymer film

5. Dual potentio galvanostat

6. Function generator

FIGS. 2(a) and (b) depict the wavelength-absorbance curves representingthe electrochromic properties of the polymer film of the3,4-asymmetrically substituted pyrrole compounds, which is obtained inExample 1. The numerals affixed to each curve stand for voltage (×10⁻¹V).

FIGS. 3(a) and(b) show the IR absorption spectra of the monomers ofSamples 1-6 and 1-7 used in Example 1 and formed polymers, respectively.

MOST SUITABLE FORMS FOR EXECUTION OF INVENTION

In the method for the preparation of the polymer represented by theaforementioned general formula (2) by the electrochemical polymerizationof this invention, the conductive salt used is a salt made by

(a) at least a cation selected from the group consisting of H⁺, Li⁺,Na⁺, K⁺, R'₄ N⁺ and R'₄ P⁺ (where R' is hydrogen atom, an alkyl radical,a cycloalkyl radical or aryl radical with no mutual relation) and

(b) at least an anion selected from the group consisting of BF₄ ⁻, AsF₄⁻, AsF₆ ⁻, SbF₆ ⁻, SbCl₆ ⁻, PF₆ ⁻, ClO₄ ⁻, HSO₄ ⁻ and SO₄ ²⁻.

In the said method, a solution of which 0.001-1 Mol/l of the aboveconductive salt is dissolved is used as an electrolyte, to which 0.001-1Mol/l of the 3,4-substituted pyrrole compound represented by theaforementioned general formula (1) is added, d.c. current is applied todeposit the polymer represented by the aforementioned general formula(2) on the surface of the anode, and the polymer grows to be film.

A solvent for the electrolyte can be any which can dissolve the3,4-substituted pyrrole compound represented by the aforementionedgeneral formula (1), and applicable solvents include organic solventssuch as acetonitrile, benzonitrile, propylene carbonate,dimethylformamide, tetrahydrofuran, nitrobenzene, methylene dichloride,chloroform or ethylene dichloride, water, or their mixtures.

Such employed conditions as the type of conductive salt and solvent,applied current or voltage may differ depending on the type of3,4-substituted pyrrole compound of material used.

In the method for the preparation of the polymer represented by theaforementioned general formula (2) by the chemical oxidation method, theoxidizing agent used has no particular limitations, if having oxidationpotential higher than that of the material 3,4-substituted pyrrolecompound, and includes a strong oxidizing agent such as Fe³⁺ compounds,H₂ O₂, S₂ O₈ ²⁻ compounds, Cl₂ or Br₂, highly oxidized oxy acid iondonating compounds such as RuO₄ ⁻ compounds, OSO₄ ⁻ compounds or MnO₄ ⁻compounds, or noble metal acid ion donating compounds such as IrCl₆ ²⁻compounds, PtCl₆ ²⁻ compounds, PdCl₄ ²⁻ compounds or AuCl₄ ²⁻ compounds.Such compounds as ruthenium (III) tris (batho phenanthroline sulfonicacid) and ruthenium (III) tris (bipyridinc sulfonic acid) are preferredexamples in particular.

In the chemical oxidation method, the reaction can be carried out eitherin a solvent system or in a non-solvent system. The polymer is directlyobtained in the form of powder or solid film.

Any solvents, which do not react with the oxidizing agent, can be usedas reaction solvents with no particular limitations. The preferred arewater, lower alcohols, acetonitrile, chloroform, or their mixtures.

In the solvent system reaction, the material pyrrole compound andoxidizing agent have no particular limitations on concentration, and canbe reacted within a range of 0.001 mol/l to saturated solution,respectively.

In the polymers obtained in the methods mentioned above, the anionspecies of the conductive salt or oxidizing agent, which is used in thereaction, are doped.

Of the polymers of this invention, particularly the polymers of pyrrolecompounds, which are asymmetrically substituted at C₃ and C₄ and have anelectron attractive radical at one of the positions, haveoxidation-reduction potential fairly greatly shifted to the positiveside, compared with other pyrrole compounds. The potential is relativelydifferent from the oxidation-reduction potential of oxygen or water. Asa result, the polymers are stable in the air and display clearelectrochromism.

If the Hammett's substituent constant (σp) of the electron attractivegroup is less than 0.30, the oxidation-reduction potential of thepolymer becomes close to that of oxygen or water and the polymer is notstable in the air in the undoping state. If the constant exceeds 0.80,the polymerization becomes hard to carry out, and thus usable polymerscannot be produced with good reproducibility.

Of the polymers of this invention, the polymers of pyrrole compounds, atleast one of whose substituents at C₃ and C₄ is an acid group such as--COOH or --CH₂ COOH (if only one of them is the stated substituent, theother is hydrogen, an alkyl radical having from 1 to 3 carbon atoms, ora phenyl radical), have a characteristic of being soluble in alkalineaqueous solvent. This is considered to be attributable to the acid groupin the polymer.

A preferred alkaline reagent used to dissolve the polymers soluble in analkaline aqueous solvent includes an alkaline metal hydroxide such asLi, Na, K, Cs or Rb, an ammonia or tetra alkyl ammonium hydroxideaqueous solution, or an alcoholic aqueous alkaline solution. The amountof the reagent used should be larger than the neutralization equivalentof the acid group of the polymer.

The concentration of the polymer in the dissolving solution can bearbitrarily adjusted unpending on the application purposes. Theneutratization or acidification of the dissolving solution results inreproducing the polymer of the undoping state in the form of powder orsolid film. Thus, the polymer can be changed to the doping stateelectrochemically or chemically by a known method.

The molecular weight distribution of the dissolving solution can bemeasured by gel-permeation chromatography (GPC).

The molecular weight distribution of the polymer obtained by theoxidative polymerization can be changed by such conditions aselectrolysis temperature, anodic current density or monomerconcentration. In the present invention, polymer whose weight averagemolecular weight is 1,000 to 1,000,000, particularly 1,000 to 100,000,is preferred. Polymers of less than 1,000 of the weight averagemolecular weight are not favorable because of inferior properties. Ifthe weight average molecular weight exceeds 1,000,000, the polymers arenot also favorable because of difficult handling due to high viscosity.The molecular weight is impossible to be indicated for the pyrrolepolymers insoluble in alkaline aqueous solvent because of difficultmolecular weight measurement.

This invention relates to the laminates made by forming theaforementioned polymer film on electrode plates.

For the said laminates, various types of metal or glass plates, on whichconductive film such as ITO (indium oxide with doped tin) film or NESA(tin oxide in which such element as antimony is doped) film is formed,can be used as electrodes.

In the method for the preparation of polymer by the aforementionedelectrolytic oxidation method, the employment of an electrode on whichthe polymer film is to be formed as an anode allows to form the polymerfilm on the said anode for easily obtaining the laminate.

Of the polymers obtained by the chemical oxidation method, if polymerinsoluble in solvent is used, the laminate can be produced in such amethod that the stated polymer is pressure molded to film to pressinglyadhere on an electrode plate via conductive paste or the polymer iscompression molded directly on an electrode plate on which conductivepaste is applied.

A polymer substance with ability to form film and an oxidizing agent aresolved in a common solvent and cast on an electrode in order to formfilm. The vapor of a pyrrole compound used as a material is made contactwith the obtained cast film to react to produce the laminate.

Compared with this, polymer soluble in alkaline aqueous solvent can beapplied or printed on the conductive surface of e.g. a metal plate ortransparent conductive glass. The applied surface is dried and then keptin an acid gas atmosphere, resulting in forming semiconductor filminsoluble in solvent. The film can be doped by a known method forconverting to the laminate.

The obtained laminate is stable in the air, and displays clearelectrochromism when changed between the doping state (oxidation state)and the undoping state (reduction state).

The polymer soluble in alkaline aqueous solvent can be applied orprinted on or penetrated into an insulating substrate of plastic orceramic. The semiconductor film insoluble in solvent, which is obtainedin a similar manner to the above, is difficult to be dopedelectrochemically, and is thus doped chemically with e.g. iodine (I₂)vapor for converting to the laminate.

As mentioned above, the employment of polymer soluble in alkalineaqueous solution allows to form conductive film on desired substratesurface with desired pattern. This invention has the effect as this. Inaddition, the conductive film produced from the polymer, thanks to thepossession of an acid group capable of using as a reaction active sitein every repeated unit, can be chemically reacted with other functiongenerating reagents.

EXAMPLES

The invention is further illustrated by reference to the followingexamples. The range of the invention is not limited by the followingexamples.

EXAMPLE 1

Electrochemical polymerization and preparation of laminates

Sample 1-1.

An ITO coated glass (4 cm²) used as an anode, and a platinum and a KClsaturated calomel electrodes employed as a cathode and a referenceelectrode, respectively, were set in an electrolytic cell of 100 ml incapacity. Purified methyl, 4-methylpyrrole-3-carboxylate of 348 g(2.5×10⁻³ mole) and tetrabutyl ammonium perchlorate of 0.855 g (2.5×10⁻³mole) were dissolved in 50 ml of acetonitrile to use as an electrolyte,which was placed in the cell.

Nitrogen gas was introduced into the electrolytic cell for eliminatingair, and a constant current of 1.0 mA was applied for 40 seconds toobtain a laminate (Sample 1-1) of which red polymer film was formed onthe surface of the ITO coated glass of the anode.

The pyrrole compound used as a material and the obtained polymer filmwere measured for the following characteristics.

The measured results are shown in Table 1.

(a) Oxidation potential of material pyrrole compound

Measured by using a dual potentio-galvanostat (OPGS-1)-functiongenerator (Nikko Keisoku Co.) and an XY recorder.

(b) Polymer film conductivity measurement

Carried out by 4 probe method according to Van der Pauw.

(c) Oxidation reduction potential of polymer film

Measured by using the same measuring instruments used for the aboveoxidation potential measurement of the material pyrrole compound.

(d) Electrochromic properties of polymer film

A device shown in attached FIG. 1 was used. The voltage was manuallychanged by 100 mV, and, when the current valve of the potentiostatbecame nearly constant, a UV chart was drawn for the absorbance (between350-750 nm), in order to indicate the relationship between thewavelength and absorbance.

The relationships between the wavelength and absorbance are shown inFIGS. 2(a) and (b). FIG. 2(a) shows the relationship between thewavelength and absorbance when the state is changed from reduction tooxidation, and FIG. 2(b) is from oxidation to reduction.

Sample 1-2

The same procedure as for the preparation of Sample 1-1 was repeatedexcept that tetrabutyl ammonium tetrafluoroborate was employed as aconductive salt, resulting in obtaining a laminate (Sample 1-2) of whichred polymer film was formed on the surface of the ITO coated glass. Thevarious properties of formed polymer film were measured similarly toSample 1-1. The measured results are shown in Table 1, together with theproperties of the material compound.

Sample 1-3

The same procedure as for the preparation of Sample 1-1 was repeatedexcept that ethyl, 4-methyl pyrrole-3-carboxylate of 0.385 g (2.5×10⁻³mole) was employed as 3,4-substituted pyrrole compound, resulting inobtaining a laminate (Sample 1-3) of which red polymer film was formedon the surface of the ITO coated glass. The various properties of thepolymer film were measured similarly to Sample 1-1. The measured resultsare shown in Table 1, together with the properties of the materialcompound.

Sample 1-4

The same procedure as for the preparation of Sample 1-1 was repeatedexcept that octyl, 4-methyl pyrrole-3-carboxylate of 0.593 g (2.5×10⁻³mole) was employed as a 3,4-substituted pyrrole compound, resulting inobtaining a laminate (Sample 1-4) of which brown polymer film was formedon the surface of the ITO coated glass. The various properties of thepolymer film were measured similarly to Sample 1-1. The measured resultsare shown in Table 1, together with the properties of the materialcompound.

Sample 1-5

The same procedure as for the preparation of Sample 1-1 was repeatedexcept that 4-methyl pyrrole-3-carboxylic acid of 0.313 (2.5×10⁻³ mole)was employed as a 3,4-substituted pyrrole compound, resulting inobtaining a laminate (Sample 1-5) of which reddish purple polymer filmwas formed on the surface of the ITO coated glass. The variousproperties of the polymer film were measured similarly to Sample 1-1.The measured results are shown in Table 1, together with the propertiesof the material compound.

Sample 1-6 to 1-9

The same procedures as for the preparation of Sample 1-1 were repeatedexcept that a 3,4-asymmetrically substituted pyrrole compound whosecombination of the substituents at C₃ and C₄ was different was employedas a material, resulting in obtaining laminates (Samples 1-6 to 1-9) ofwhich various types of polymer film were formed on the surface of theITO coated glass.

The various properties of the polymer films were measured similarly toSample 1-1. The measured results are shown in Table 1, together with theproperties of the material compounds.

The pyrrole compounds and their polymers of Samples 1-6 and 1-7 weremeasured for the IR absorption spectra by using FT-IR 20D (Nicolet JapanCo.) and by KBr tablet method. The measured IR absorption spectra areshown in FIGS. 3(a) and (b). An absorption based on the 2,5-Hout-of-plane vibration is observed at 700-800 cm⁻¹ in the IR spectra ofthe monomers but disappear after polymerized. Thus it is confirmed thatpolymer of which C₂ and C₅ are bonded to form a chain is obtained.

Comparison sample 1-1

The same procedure as for the preparation of Sample 1-1 was repeatedexcept that pyrrole (symmetrical and not substituted at C₃ and C₄) wasemployed as a pyrrole compound of a material, resulting in obtaining alaminate (Comparison sample 1-1) of which black polymer film was formedon the surface of the ITO coated glass.

The various proporties of both pyrrole of the material and the obtainedpolymer film were measured similarly to Sample 1-1.

The measured various properties of the polymer film are shown in Table1, together with the properties of the material compound.

Comparison sample 1-2

The same procedure as for the preparation of Sample 1-1 was repeatedexcept that 3-methyl pyrrole whose substituent at C₃ is a methyl radical(σp=-0.17), an electron donative substituent, was employed as a pyrrolecompound of a material, resulting in obtaining a laminate (Comparisonsample 1-2) of which polymer film was formed on the surface of the ITOcoated glass.

The various properties of the polymer film and the pyrrole compound weremeasured similarly to Sample 1-1.

The measured various properties of the polymer film are shown in Table1, together with the properties of the material compound.

                                      TABLE 1                                     __________________________________________________________________________     ##STR3##                                                                     __________________________________________________________________________              Pyrrole compounds                                                                                             Oxidation                           Sample    Substituent                     Potential                           No.       X        Y*.sup.1 Z   Conductive Salt                                                                         (V)                                 __________________________________________________________________________    1-1       CH.sub.3 COOCH.sub.3                                                                            H   (C.sub.4 H.sub.9).sub.4 NClO.sub.4                                                      1.1                                 1-2       CH.sub.3 COOCH.sub.3                                                                            H   (C.sub.4 H.sub.9).sub.4 NBF.sub.4                                                       1.1                                 1-3       CH.sub.3 COOC.sub.2 H.sub.5                                                                     H   (C.sub.4 H.sub.9).sub.4 NClO.sub.4                                                      1.1                                 1-4       CH.sub.3 COOC.sub.8 H.sub.17                                                                    H   (C.sub.4 H.sub.9).sub.4 NClO.sub.4                                                      1.0                                 1-5       CH.sub.3 COOH     H   (C.sub.4 H.sub.9).sub.4 NClO.sub.4                                                      0.9                                 1-6       CH.sub.3 COC.sub.2 H.sub.5                                                                      H   (C.sub.4 H.sub.9).sub.4 NClO.sub.4                                                      1.1                                 1.7       CH.sub.3 CN       H   (C.sub.4 H.sub. 9).sub.4 NClO.sub.4                                                     1.45                                1-8       C.sub.3 H.sub.7                                                                        COOC.sub.2 H.sub.5                                                                     H   (C.sub.4 H.sub.9).sub.4 NClO.sub.4                                                      1.05                                1-9       C.sub.6 H.sub.5CH.sub.2                                                                COOCH.sub.3                                                                            H   (C.sub.4 H.sub.9).sub.4 NClO.sub.4                                                      1.1                                 Comparison                                                                    1-1       H        H        H   (C.sub.4 H.sub.9).sub.4 NClO.sub.4                                                      0.8                                 1-2       H        CH.sub.3 H   (C.sub.4 H.sub.9).sub.4 NClO.sub.4                                                      0.7                                 __________________________________________________________________________           Pyrrole Compound Polymer Film                                                        Oxidation Reduction                                                           Potential                                                                     Anode Peak                                                                           Cathode Peak                                                                         Electrochromic Property                           Sample Conductivity                                                                         Voltage                                                                              Voltage                                                                              *.sup.2   *.sup.3                                 No.    (S cm.sup.-1)                                                                        Epa: (mV)                                                                            Epc: (mV)                                                                            (nm)      (nm)      *.sup.4                       __________________________________________________________________________    1-1    1.0 × 10.sup.0                                                                 +820   +500   red: 530  yellowish green: 406                                                                    O                             1-2    0.5 × 10.sup.0                                                                 +820   +500   red: 530  yellowish green: 406                                                                    O                             1-3    1.2 × 10.sup.-3                                                                +740   +420   red: 550  yellowish green: 380                                                                    O                             1-4    1.1 × 10.sup.-4                                                                +850   +600   brown: 540                                                                              yellowish green: 390                                                                    O                             1-5    0.4 × 10.sup.0                                                                 +750   +560   reddish purple: 570                                                                     yellow: 390                                                                             O                             1-6    1.2 × 10.sup.-3                                                                +840   +500   reddish purple: 550                                                                     yellowish green: 380                                                                    O                             1-7    <10.sup.-6                                                                            +1200 +650   green: -- brown: -- O                             1-8    9.3 × 10.sup.-5                                                                 +1000 +500   reddish brown: --                                                                       yellowish green: --                                                                     O                             1-9    --      +1050 +750   red: --   yellow: --                                                                              O                             Comparison                                                                    1-1    0.9 × 10.sup.2                                                                 +400   +0     black: -- yellowish green: 420                                                                    X                             1-2    --     +80    +40    --        --        X                             __________________________________________________________________________     *.sup.1 Hammett's Substituent Constant COOCH.sub.3 ; 0.46, COOC.sub.2         H.sub.5 ; 0.46, COOC.sub.8 H.sub.17 ; 0.46, COOH; 0.42, COC.sub.2 H.sub.5     ; 0.45, CN; 0.66, H; 0, CH.sub.3 ; -0.17                                      *Stability of electrochromic property                                         O: Capable of leaving stable in the air for a week in the oxidation state     or reduction state.                                                           X: Stable in the oxidation state, but, in the reduction state, impossible     to leave because oxidized by the air.                                         *.sup.2 Color in Oxidation State: Max. Absorption Wavelength                  *.sup.3 Color in Reduction State: Max. Absorbtion Wavelength                  *.sup.4 Stability in air                                                 

EXAMPLE 2

Chemical oxidative polymerization

Sample 2-1

To 46 ml of acetonitrile solution containing 0.50 g of 4-methylpyrrole-3-carboxylic acid and 1.38 g of tetraethyl ammonium-para toluenesulfonate was added 4.46 g of anhydrous ferric chloride, and theresulting solution was heated at the boiling point of acetonitrile(81.6° C.) for 13 hours.

After cooled, the solution was filtrated with No. 2 qualitative filterpaper, washed with acetonitrile, and then heated to dry by anincandescent lamp to give 0.86 g of black product. Of it, 222 mg waspulverized in mortar, made contact with iodine vapor for 3 days, andthen formed to be a disc of 10 mmφ in diameter and 1.87 mm thick byusing a tablet forming machine for IR absorption spectrum sample. Thedisc was further made contact with iodine vapor for 3 days and itsvolume resistibility was measured by the 4 probe method according to Vander Pauw. The conductivity (S cm⁻¹) was 2.9×10⁻⁴.

Sample 2-2

0.19 g of 4-phenyl pyrrole-3-carboxylic acid and 2.76 g of stannicchloride were dissolved in 30 ml of chloroform to heat to reflux at theboiling point of chloroform, 61.2° C., for 6 hours. After cooling, theresultng solution was filtrated. The residue on the surface of thefilter paper was washed with chloroform and heated to dry by anincandescent lamp to give 220 mg of black product.

Of it, 186 mg was pulverized in a mortar and the conductivity (S cm⁻¹)was measured in a similar way to Sample 1-1. The result was 1.3×10⁻⁴.(However the size of the formed disc was 10 mmφ in diameter×1.32 mmthick.)

EXAMPLE 3

Polymer soluble in alkaline aqueous solvent.

Sample 3-1

An ITO coated glass (4 cm²) used as an anode, and platinum and KClsaturated calomel electrodes employed as a cathode and a referenceelectrode, respectively, were set in an electrolytic cell of 100 ml incapacity. Purified 4-methyl pyrrole-3-carboxylic acid of 6.25×10⁻² g and1.71 g of (n-Bu)₄ NClO₄ were dissolved in 50 ml of acetonitrile to useas an electrolyte, which was placed in the cell.

Both electrodes were dipped in the electrolyte so as to be immersed 20mm depth from the lower side of the electrode. Nitrogen gas wasintroduced to remove dissolved oxygen and the air is shut down frommixing, then current of 2 mA was applied for 10 minutes.

Reddish purple polymer was electrodeposited on the ITO coated glass ofthe anode. The anode was pulled up from the electrolyte, washed withacetone and wind dried to give 1.34 mg of weight increase. This value islarger than the theoretical value: ##EQU1## Because it is consideredthat the washing with acetone cannot remove the doped ClO₄ ⁻ ions. Thepolymer, when immersed in 0.5 ml of 2N-NaOH aqueous solution, slowlydissolves to give a transparent greenish yellow solution. This solutionwas applied to a platinum wire of 1 mmφ×7 mm and made contact withhydrogen chloride gas, resulting in the recognition of black polymerformed on the surface the platinum wire. This platinum wire was employedas an anode, and a platinum wire was used as a cathode and an Ag/AgClelectrode as a reference electrode, and cyclic voltammetry was performedfrom -0.4 V to +1.9 V (vs Ag/AgCl) to give curves almost equal to thecyclic voltammograms directly obtained by the electrochemicalpolymerization using (n-Bu)₄ NClO₄ as a supporting electrolyte andacetonitrile as a solvent.

The molecular weight of the obtained polymer was measured by GPC to giveweight average molecular weight of approximately 2,800.

The molecular weight was measured under the conditions: high-speedliquid chromatography LC-6A (Shimadzu), column; Asahi pack GS-520 (AsahiChemical lndustry, vinyl alcohol copolymer) of 7.6 mmφ×500 mm,developing solution; sodium phosphate system, a buffer of pH 11.4, andat room temperature. The detection was carried out at the wavelength of250 nm and the molecular weight was calculated by using polystyrenesodium sulfonate as a standard polymer substance.

Sample 3-2

Equipment similar to that used for Sample 3-1 was used, an acetonitrilesolution containing 0.01 mole/l of 4-propyl pyrrole-3-carboxylic acidand 0.1 mole/l of (n-Bu)₄ NBF₄ was employed as an electrolyte, and acurrent was applied intermittently at 6 mA×60 sec×11 times to form 1.38g of polymer on the anode plate. When the electrode coated with thispolymer was immersed in a 1/20 N NaOH aqueous solution, the polymer wasimmediately peeled off from the electrode plate and slowly dissolved togive a transparent dark greenish yellow solution.

The molecular weight of the obtained polymer was measured by GPC to giveweight average molecular weight of approximately 5,000.

Sample 3-3

The same experiment as for the preparation of sample 3-1 were repeatedexcept that an acetonitrile solution containing 0.1 moles of 4-phenylpyrrole-3-carboxylic acid and 0.1 mole/l of (n-Bu)₄ NClO₄ was employedas an electrolyte. A current of 6 mA was continuously applied for 600seconds to give 2.2 mg of polymer on the anode plate. When this anodeplate was dipped in a mixture solution of 10 ml of 2N-NaOH aqueoussolution and 5 ml of ethanol, a green solution, in which most of thepolymer were dissolved but black fine particles were partly suspended,was obtained. The solution was filtrated with filter paper to give atransparent solution.

The molecular weight of the obtained polymer was measured by GPC to giveaverage molecular weight of approximately 3,500.

Sample 3-4

2 mg of the polymer of Example 2 (Sample 2-1) obtained by the chemicaloxidative polymerization were dissolved in 5 ml of 2N-NaOH aqueoussolution and turned blackish green. The resulting solution was filtratedwith 0.4μ micron filter and the molecular weight was measured by GPC togive weight average molecular weight of approximately 2,800.

Similarly, 2 mg of the polymer of Example 2 (Sample 2-2) dissolved in amixture solution of 5 ml of 2N NaOH and 10 ml of ethanol and turnedblackish green.

Industrial Applicability

The polymers of pyrrole compounds of which at least one of C₃ and C₄ issubstituted by an electron attractive group, particularly pyrrolecompounds of which only one of C₃ and C₄ is substituted, have oxidationreduction potential different from that of oxygen and water, comparedwith the polymers described in the aforementioned comparison examples,and exist stable in the air in the undoping state.

The polymers of this invention, as shown in FIG. 2, have a continuousclear visible light absorption spectrum against the voltage change, andthe spectra show almost completely reversible behavior between theoxidation and reduction states. This means, the polymers of thisinvention have clear electrochromism characeristics.

In addition, the polymers soluble in alkaline aqueous solvent have theadvantage that conductor film with a desired pattern can be formed onthe surface of a desired substrate.

Thanks to the above facts, these polymers used as laminates of whichpolymer film is formed on an electrode plate, have expectation of theapplications to optical functional components such as electrochromicdisplays, optical switches and optical memory components, and for theuse as materials for a variety of electronic devices such as sensormaterials and battery materials.

The applications as agents such as polymer electrolytes or polymerchelating agents are also expected.

What is claimed is:
 1. New polymers of 3,4-substituted pyrrole compounds, which are represented by the general formula: ##STR4## where at least one of X and Y is an electron attractive substituent with 0.03-0.80 of Hammett's substituent constant (σp), if only either X or Y is the above electron attractive substituent, the other one is hydrogen, an alkyl radical, a benzyl radical or a non-substituted or a phenyl radical substituted by a halogen, nitro, cyano methoxy or ethoxy radical; Z is hydrogen or a lower alkyl radical; and n is an integer of 2 or larger.
 2. New polymers according to claim 1 in which either X or Y is an electron attractive substituent with 0.3-80 of Hammett's substituent constant (σp) and the other is hydrogen, an alkyl radical, a benzyl radical or a non-substituted or phenyl radical substituted by a halogen, nitro, cyano, methoxy or ethoxy radical.
 3. New polymers according to claim 1 or 2 in which the electron attractive substituent is --COOH, --COOR, --NO₂, --CN, --COR, --CONH₂ or --CONHOH, where R is a straight-chain or branched alkyl radical having from 1 to 10 carbon atoms.
 4. New polymers according to claim 1 or 2 in which the repeated unit the polymers have is a 3,4-substituted pyrrole compound and of which at least one of X and Y is --COOH or --CH₂ COOH and if only either X or Y is --COOH or --CH₂ COOH, the other is hydrogen, an alkyl radical having from 1 to 3 carbon atoms or a phenyl radical, and the weight average molecular weight, Mw is 1,000 to 1,000,000 wherein the polymers are soluble in alkaline aqueous solvent. 